Dr. Bruno Maggio
Titular Professor, School Chemical of Science, National University of Cordoba. CONICET Superior Researcher
CIQUIBIC Vice-Director

TE: 0351-4334171/68 Int. 221
Fax: 03551-4334074
e-mail:bmaggio@dqb.fcq.unc.edu.ar

Dra. Graciela Borioli
CONICET Adjunt Researcher

TE: 0351-4334171/68 Int. 220
Fax: 03551-4334074
e-mail:gborioli@dqb.fcq.unc.edu.ar
 
Biological Chemistry Department, Chemical Science School, National University of Cordoba, Haya de la Torre s/n University Campus, 5000 Cordoba, Argentina.
Supramolecular regulation of the structure, dynamics and reactivity of biomembranes
A common key point for the control, regulation, transmission and transduction of molecular events to the supramolecular level in biomembranes, and the concomitant biochemical and cellular changes, is centered in understanding the structural dynamics involved in the formation, segregation, shape and topography of lipid-protein domains that are laterally and transversally segregated in the membrane. Our research is aimed at disclosing how the combination of interfacial factors such as the molecular packing density, dipolar anisotropy, conformation, surface elasticity and their modifications due to local interactions results in critical thermodynamic thresholds whereby the surface tensions can be relaxed or amplified to lateral or transverse immiscibility processes leading to segregation of domains with different dimensions, stability and long-range distribution. Within this context we study the involvement of sphingolipids and phospholipids in the regulation by the surface organization of the biological activity of membrane-associated enzymatic and non-enzymatic anphitropic proteins as both modulating and generating agents of the surface topography. At present, we specifically investigate: a) the molecular parameters determining the structural dynamics of two-dimensional compositional domains of sphingolipids and phospholipids of defined chemical structure; b) the bi-directional control between the lateral surface topography and phopholipase activity (in particular sphingomyelinase); c) the influence of the surface electrostatic on the structural dynamics of phase-segregated domains in interfaces containing sphingolipids and gangliosides; d) the interactions of integral, extrinsic and anphitropic proteins (Folch-Lees myelin porteolipid, myelin basis protein,c-Fos, c-Jun, phospholipoase A2, C and sphingomyelinase) as determinants of the interfacial organization and its control on their biological activity.
 

Interaction of transcription factors with membrane phospholipids
 
   The transcription factors c-Fos and c-Jun are tensioactive and can thus selectively interact with membrane phospholipids, which enables them to have a function at this level. Moreover, c-Fos regulates phospholipid metabolism associated to endoplasmic reticulum independently of transcriptional regulation. Additionally its modulation of diverse phospholipases activity illustrates its capacity to participate in membrane processes. This modulatory effect was adscribed to the induction of the lipid substrate interfacial organization.
Our studies aim at the nature of the interaction of transcription factors with membrane phospholipids, and between them to form AP-1 transcriptional complexes. We use micro, meso and nanotechniques on monolayers end vesicles, such as thermodynamic surface parameters monitoring, epifluorescence and Brewster angle microscopy, calorimetry, fluorescence and IR spectroscopy and Small Angle X Ray Scattering.